capacity

Capacity describes your ability to do something or the amount something can hold. If your bird cage is at full capacity, you can't stuff one more feathered friend in there without causing birdie claustrophobia.

From the Latin word capacitatem meaning “breadth, capacity,” capacity is a noun that in the simplest sense means "ability" or "capability": the capability of a room to hold a certain number of people, the ability of a law to change crime rates, your ability to pick up foreign languages. You might hear about factories working at "full capacity" — that means at full speed, producing as much as they possibly can.

n
(computer science) the amount of information (in bytes) that can be stored on a disk drive

(computer science) the usable capacity of a disk drive; the amount of space that is left after the sector headings and boundary definitions and timing information have been added by formatting the disk